Motor and cognitive placebo-/nocebo-responses in hypokinetic-rigid Parkinson's disease patients with deep brain stimulation

Introduction: In Parkinson's disease (PD) placebo and nocebo responses have been observed repeatedly. Patients' expectation is considered a main mechanism mediating those responses. Subthalamic nucleus (STN) deep brain stimulation (DBS) improves proximal more than distal movements and can impair verbal fluency (VF) as a potential side-effect. In the present study, we investigated how expectation modulates the effect of STN-DBS on motor and non-motor functions particularly affected by STN-DBS. Methods: In a within-subject-design, expectation regarding the effect of STN-DBS on motor symptoms was manipulated by ver…